AK+Kernel: Disallow implicitly lifting pointers to OwnPtr's

This doesn't really _fix_ anything, it just gets rid of the API and
instead makes the users explicitly use `adopt_own_if_non_null()`.

AK/OwnPtr.h

@@ -15,13 +15,12 @@ template<typename T>
 class OwnPtr {
 public:
     OwnPtr() = default;
-    explicit OwnPtr(T* ptr)
-        : m_ptr(ptr)
+
+    OwnPtr(decltype(nullptr))
+        : m_ptr(nullptr)
     {
-        static_assert(
-            requires { requires typename T::AllowOwnPtr()(); } || !requires(T obj) { requires !typename T::AllowOwnPtr()(); obj.ref(); obj.unref(); },
-            "Use RefPtr<> for RefCounted types");
     }
+
     OwnPtr(OwnPtr&& other)
         : m_ptr(other.leak_ptr())
     {
@@ -96,13 +95,7 @@ public:
         return *this;
     }
 
-    OwnPtr& operator=(T* ptr)
-    {
-        if (m_ptr != ptr)
-            delete m_ptr;
-        m_ptr = ptr;
-        return *this;
-    }
+    OwnPtr& operator=(T* ptr) = delete;
 
     OwnPtr& operator=(std::nullptr_t)
     {
@@ -181,6 +174,20 @@ public:
         ::swap(m_ptr, other.m_ptr);
     }
 
+    static OwnPtr lift(T* ptr)
+    {
+        return OwnPtr { ptr };
+    }
+
+protected:
+    explicit OwnPtr(T* ptr)
+        : m_ptr(ptr)
+    {
+        static_assert(
+            requires { requires typename T::AllowOwnPtr()(); } || !requires(T obj) { requires !typename T::AllowOwnPtr()(); obj.ref(); obj.unref(); },
+            "Use RefPtr<> for RefCounted types");
+    }
+
 private:
     T* m_ptr = nullptr;
 };
@@ -195,7 +202,7 @@ template<typename T>
 inline OwnPtr<T> adopt_own_if_nonnull(T* object)
 {
     if (object)
-        return OwnPtr<T>(object);
+        return OwnPtr<T>::lift(object);
     return {};
 }
 

Kernel/FileSystem/Plan9FileSystem.cpp

@@ -576,7 +576,7 @@ KResult Plan9FS::read_and_dispatch_one_message()
         auto completion = optional_completion.value();
         ScopedSpinLock lock(completion->lock);
         completion->result = KSuccess;
-        completion->message = new Message { buffer.release_nonnull() };
+        completion->message = adopt_own_if_nonnull(new Message { buffer.release_nonnull() });
         completion->completed = true;
 
         m_completions.remove(header.tag);

Kernel/FileSystem/ProcFS.cpp

@@ -1102,7 +1102,7 @@ KResult ProcFSInode::refresh_data(FileDescription& description) const
     }
 
     if (!cached_data)
-        cached_data = new ProcFSInodeData;
+        cached_data = adopt_own_if_nonnull(new ProcFSInodeData);
     auto& buffer = static_cast<ProcFSInodeData&>(*cached_data).buffer;
     if (buffer) {
         // If we're reusing the buffer, reset the size to 0 first. This

Kernel/Interrupts/SpuriousInterruptHandler.cpp

@@ -18,7 +18,7 @@ UNMAP_AFTER_INIT void SpuriousInterruptHandler::initialize(u8 interrupt_number)
 void SpuriousInterruptHandler::register_handler(GenericInterruptHandler& handler)
 {
     VERIFY(!m_real_handler);
-    m_real_handler = &handler;
+    m_real_handler = adopt_own_if_nonnull(&handler);
 }
 void SpuriousInterruptHandler::unregister_handler(GenericInterruptHandler&)
 {

Kernel/Syscalls/profiling.cpp

@@ -108,7 +108,7 @@ KResultOr<int> Process::sys$profiling_free_buffer(pid_t pid)
         {
             ScopedCritical critical;
 
-            perf_events = g_global_perf_events;
+            perf_events = adopt_own_if_nonnull(g_global_perf_events);
             g_global_perf_events = nullptr;
         }
 

Kernel/VirtIO/VirtIOQueue.cpp

@@ -22,9 +22,9 @@ VirtIOQueue::VirtIOQueue(u16 queue_size, u16 notify_offset)
     // TODO: ensure alignment!!!
     u8* ptr = m_queue_region->vaddr().as_ptr();
     memset(ptr, 0, m_queue_region->size());
-    m_descriptors = reinterpret_cast<VirtIOQueueDescriptor*>(ptr);
-    m_driver = reinterpret_cast<VirtIOQueueDriver*>(ptr + size_of_descriptors);
-    m_device = reinterpret_cast<VirtIOQueueDevice*>(ptr + size_of_descriptors + size_of_driver);
+    m_descriptors = adopt_own_if_nonnull(reinterpret_cast<VirtIOQueueDescriptor*>(ptr));
+    m_driver = adopt_own_if_nonnull(reinterpret_cast<VirtIOQueueDriver*>(ptr + size_of_descriptors));
+    m_device = adopt_own_if_nonnull(reinterpret_cast<VirtIOQueueDevice*>(ptr + size_of_descriptors + size_of_driver));
 
     for (auto i = 0; i + 1 < queue_size; i++) {
         m_descriptors[i].next = i + 1; // link all of the descriptors in a line